Liquid supply system

ABSTRACT

A liquid supply system that can be cooled efficiently. The liquid supply system  10  includes a container  130  having an inlet  131   b  and an outlet  131   c  for liquid and provided with a pump chamber P 1 , P 2  inside it, an outlet pipe  320  through which liquid discharged from the outlet  131   c  is brought to outside, a fluid channel through which liquid flows, the fluid channel leading out of the inlet  131   b , passing through the pump chamber P 1 , P 2 , and extending vertically downward from the pump chamber P 1 , P 2  to the outlet  131   c , and a gas vent pipe  602  connecting a first orifice  601  and a second orifice  604 , the first orifice  601  being disposed in the fluid channel and the second orifice  604  being disposed in the fluid channel downstream of the first orifice  601 . The second orifice  604  is located at vertically higher level than the first orifice  601.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/JP2018/003632, filed Feb. 2, 2018 (now WO 2018/143421A1), whichclaims priority to Japanese Application No. 2017-019040, filed Feb. 3,2017. The entire disclosures of each of the above applications areincorporated herein by reference.

FIELD

The present disclosure relates to a liquid supply system used to supplyliquid.

BACKGROUND

A liquid supply system using a bellows pump including pump chambersformed by bellows is known as a system used to cause a liquid to flow ina circulation fluid passage (see Patent Literature 1 in the citationlist below). This system has two pump chambers arranged one above theother along the vertical direction. The bellows that forms each pumpchamber is fixedly attached to a shaft that is driven by an actuator tomove upward and downward. The bellows expands and contracts with theupward and downward motion of the shaft.

The pump apparatus is housed in a vacuum container for heat insulation,above which the actuator is disposed. For the purpose of helping heatinsulation, an inlet pipe for supplying liquid to the pump apparatusfrom outside and an outlet pipe for discharging liquid from the pumpapparatus to outside may be connected to the pump apparatus at locationsas remote as possible from the outside air. For this reason, the inletpipe and the outlet pipe are arranged to enter into the vacuum containerfrom above, extend to a location lower than the pump apparatus, thenturn in a U-shape, and be connected to openings provided on the bottomof the pump apparatus. This shape of the pipes connected to the pumpapparatus provides insulation against heat coming from outside. Thebellows pump structured as above can be suitably used for the purpose ofsupplying a cryogenic liquid such as liquid nitrogen or liquid helium toan apparatus to be cooled, such as a superconducting device.

When a bellows pump assembled or maintained in an ordinary temperatureenvironment is used to supply low temperature liquid, it is necessary tocool the components of the pump apparatus from the ordinary temperatureto the temperature of the low temperature liquid. If the temperature ofthe components is high, the low temperature liquid will evaporate in abellows chamber to be in a mixed state of gas and liquid, impairing theoperation of the pump. One method of cooling the pump apparatus iscausing low temperature liquid to flow in the pump apparatus to causeheat exchange between the components of the pump apparatus and the lowtemperature liquid, thereby gradually lowering the temperature of thecomponents. In the process of this method, the low temperature liquidflowing into the pump apparatus from its bottom fills the interior ofthe pump chamber; specifically the liquid firstly fills the lowerbellows pump chamber and then the upper bellows pump chamber, as thelevel of the low temperature liquid increases. However, cooling thebellows pump to an operable temperature by this cooling method takes along time.

One reason for this is that when the level of the low temperature liquidin the pump apparatus is low, the contact area of the components of thepump and the low temperature liquid is small, and the efficiency ofcooling is low in the early stage of the cooling process. Another reasonis that when the temperature of the components of the pump is high, thelow temperature liquid evaporates to create gas staying in the pumpchambers, which blocks the entrance of the low temperature liquid.Moreover, since the two bellows pump chambers are arranged one (thefirst pump chamber) above the other (the second pump chamber), theliquid supplied into the pump apparatus flows out through the dischargeport of the second (or lower) pump chamber, and the liquid level is slowto rise above the height of the discharge port of the second pumpchamber. Therefore, if the first pump chamber is located above thedischarge port of the second pump chamber, cooling of the first pumpchamber takes a long time. Moreover, the components of the pump are madeof a metal material(s) having high rigidity in order to allow highdischarge pressure, and when low temperature liquid comes in contactwith the surface of the metal, which has high heat conductivity, thesurface of the metal is covered with gas produced by evaporation of thelow temperature liquid. This phenomenon is called film boiling. The gaslayer produced on the metal surface in this way functions as a heatinsulation layer to block heat transfer between the low temperatureliquid and the components of the pump.

CITATION LIST Patent Literature [PTL 1] WO 2016/006648 SUMMARY TechnicalProblem

An object of the present disclosure is to provide a liquid supply systemthat can be cooled efficiently.

Solution to Problem

To achieve the above object, the following features are adopted.

An aspect of the present disclosure is a liquid supply system comprises:a container having an inlet and an outlet for liquid and provided with apump chamber inside it; an outlet pipe through which liquid dischargedfrom the outlet is brought to outside; a fluid channel through whichliquid flows, the fluid channel leading out of the inlet, passingthrough the pump chamber, and extending vertically downward from thepump chamber to the outlet; and a gas vent pipe having a first orificedisposed in the fluid channel and a second orifice disposed in the fluidchannel downstream of the first orifice, wherein the second orifice islocated at vertically higher level than the first orifice.

The liquid supply system has a fluid channel in which liquid flowsvertically downward from the pump chamber. Liquid staying in a lowerportion in such system may prevent gas generated in the container frombeing discharged from the container. Such a situation may occur, forexample, when liquid supplied to the liquid supply system for thepurpose of cooling evaporates in the container during a cooling processfor making the liquid supply system in an ordinary temperatureenvironment operable for the purpose of circulation of a cryogenicliquid.

When gas is present in the container of the liquid supply system, namelywhen gas is present in the fluid passage passing through the pumpchamber, the gas can be discharged out of the container through the gasvent pipe. Thus the system can prevent gas from staying in thecontainer. If gas stays in the container, the gas may hamper feeding oflow temperature liquid during a cooling process of the system, leadingto an increase in the time taken to cool the system. The presentdisclosure can prevent gas from staying in the container, thus the timeneeded for cooling can be reduced. Hence, the liquid supply system canbe cooled efficiently by supplying low temperature liquid into it. Thus,the present disclosure can suppress an increase in the man-hour insetting-up and maintenance of the system through reducing the time takento cool the liquid supply system in an ordinary temperature environment.Moreover, the consumption of low temperature liquid in the coolingprocess can be reduced.

The second orifice may be disposed in the outlet pipe.

This enables gas staying in the upper portion of the pump chamber to bedischarged to the outlet pipe. Thus, if the outlet pipe or a liquidsupply target is provided with a gas vent system, it can be shared, Thisreduces portions in which liquid comes in contact with the outsideenvironment from a viewpoint of the whole system, thereby heat exchangecan be reduced, leading to reduction in the consumption of lowtemperature liquid.

Another aspect of the present disclosure is a liquid supply systemhaving bellows pumps. Specifically, the liquid supply system maycomprise: a shaft member that moves vertically upward and downward inthe container; and a first bellows and a second bellows disposed oneabove the other along the vertical direction, each of which expands andcontracts with upward and downward motion of the shaft member; whereinthe pump chamber may include a first pump chamber formed by a spacesurrounding the outer circumference of the first bellows and a secondpump chamber formed by a space surrounding the outer circumference ofthe second bellows, the fluid channel may include a first fluid channelthrough which liquid flows from the inlet to the outlet via the firstpump chamber and a second fluid channel through which liquid flows fromthe inlet to the outlet via the second pump chamber, and the gas ventpipe may be provided in at least one of the first and second fluidchannels.

Although gas tends to stay in the upper pump chamber in this liquidsupply system, the gas vent pipe provided in at least one of the firstand second fluid channels can easily discharge the gas staying in thefluid channel passing through the upper pump chamber to the outside.Thus, the first and second pump chambers can be cooled efficiently bysupplying low temperature liquid into them.

The first pump chamber may be disposed above the second pump chamber,and the first orifice may be located above the outlet of the first pumpchamber.

Although gas tends to stay in a region near the outlet of the upperfirst pump chamber in this liquid supply system, the first orifice ofthe gas vent pipe located above the outlet of the first pump chamberenables gas in the container to be easily discharged.

The above-described features may be adopted in any feasible combination.

Advantageous Effects of the Disclosure

The liquid supply system according to the present disclosure can becooled efficiently.

DRAWINGS

FIG. 1 is a diagram illustrating the general configuration of a liquidsupply system in an embodiment.

FIG. 2 is a diagram illustrating the general configuration of the liquidsupply system in the embodiment.

FIG. 3 is a schematic cross sectional view of the liquid supply systemin the embodiment.

DETAILED DESCRIPTION

In the following, modes for carrying out the present disclosure will bedescribed specifically on the basis of a specific embodiment withreference to the drawings. The dimensions, materials, shapes, relativearrangements, and other features of the components that will bedescribed in connection with the embodiment are not intended to limitthe technical scope of the present disclosure only to them, unlessparticularly stated.

Embodiment

A liquid supply system in an embodiment will be described with referenceto FIGS. 1 to 3. The liquid supply system is suitably used for thepurpose of, for example, maintaining a superconducting device in anultra-low temperature state. Superconducting devices require perpetualcooling of components such as superconducting coils. Thus, a cooleddevice including a superconducting coil and other components isperpetually cooled by continuous supply of a cryogenic liquid (such asliquid nitrogen or liquid helium) to the cooled device. Specifically, acirculation fluid passage passing through the cooled device is provided,and the liquid supply system is connected to the circulation fluidpassage to cause the cryogenic liquid to circulate, thereby enablingperpetual cooling of the device to be cooled.

<Overall Configuration of the Liquid Supply System>

FIGS. 1 and 2 are schematic diagrams illustrating the overallconfiguration of the liquid supply system, where the overallconfiguration of the liquid supply system is illustrated in crosssections. FIGS. 1 and 2 illustrate the general configuration of theliquid supply system in cross sections in planes containing the centeraxis. In each of FIGS. 1 and 2, cross sections of the cylindrical liquidsupply system in different circumferential phases are illustrated in asingle drawing. Specifically, the left side of the center axis in FIGS.1 and 2 illustrates a cross section in a phase in which a gas vent pipeis clearly seen (the phase indicated by line B-B in FIG. 3), the rightside of the center axis in FIG. 1 illustrates a cross section in a phasein which a second fluid passage passing through a second pump chamber isclearly seen (the phase indicated by line D-D in FIG. 3), and the rightside of the center axis in FIG. 2 illustrates a cross section in a phasein which a first fluid passage passing through a first pump chamber isclearly seen (the phase indicated by line C-C in FIG. 3).

The liquid supply system 10 includes a main unit of the liquid supplysystem (which will be referred to as the “main system unit 100”hereinafter), a vacuum container 200 in which the main system unit 100is housed, and pipes (including an inlet pipe 310 and an outlet pipe320). The inlet pipe 310 and the outlet pipe 320 both extend into theinterior of the vacuum container 200 from outside the vacuum container200 and are connected to the main system unit 100. The interior of thevacuum container 200 is a hermetically sealed space. The interior spaceof the vacuum container 200 outside the main system unit 100, the inletpipe 310, and the outlet pipe 320 is kept in a vacuum state. Thus, thisspace provides heat insulation. The liquid supply system 10 is normallyinstalled on a horizontal surface. In the installed state, the upwarddirection of the liquid supply system 10 in FIGS. 1 and 2 is thevertically upward direction and the downward direction in FIGS. 1 and 2is the vertically downward direction.

The main system unit 100 includes a linear actuator 110 serving as adriving source, a shaft member 120 that is moved in vertically upwardand downward directions by the linear actuator 110, and a container 130.The linear actuator 110 is fixed on something suitable, which may be thecontainer 130 or something that is not shown in the drawings. Thecontainer 130 includes a casing 131. The shaft member 120 extends fromoutside the container 130 into the inside through an opening 131 aprovided in the ceiling portion of the casing 131. The casing 131 has aninlet 131 b and an outlet 131 c for liquid on its bottom. The inlet pipe310 is connected to the inlet 131 b and the outlet pipe 320 is connectedto the outlet 131 c.

Inside the casing 131 are provided a plurality of structural componentsthat compart the interior space into a plurality of spaces, whichconstitute a plurality of pump chambers, passages for liquid, and vacuumchambers providing heat insulation. In the following, the structureinside the casing 131 will be described in further detail.

The shaft member 120 has a main shaft portion 121 having a cavity in it,a cylindrical portion 122 surrounding the outer circumference of themain shaft portion 121, and a connecting portion 123 that connects themain shaft portion 121 and the cylindrical portion 122. The cylindricalportion 122 is provided with an upper outward flange 122 a at its upperend and a lower outward flange 122 b at its lower end.

The casing 131 has a substantially cylindrical body portion 131X and abottom plate 131Y. The body portion 131X has a first inward flange 131Xaprovided near its vertical center and a second inward flange 131Xbprovided on its upper portion.

Inside the body portion 131X, there are a plurality of first fluidpassages 131Xc that extend in the axial direction below the first inwardflange 131Xa and are spaced apart from one another along thecircumferential direction. The first fluid passages 131Xc connect afluid passage 131 d and an inlet 401 of a first pump chamber P1. Insidethe body portion 131X, there also are a plurality of third fluidpassages 131Xg that extend in the axial direction above the first inwardflange 131Xa and are spaced apart from one another along thecircumferential direction. The third fluid passages 131Xg are joinedwith an outlet 404 of a second pump chamber P2. Inside the body portion131X, there also is a second fluid passage 131Xd, which is an axiallyextending cylindrical space provided radially outside the region inwhich the first fluid passages 131Xc are provided. The second fluidpassage 131Xd is joined with an outlet 402 of the first pump chamber P1and extends to the level of the outlet 402 of the first pump chamber P1.The bottom portion of the casing 131 is provided with the fluid passage131 d that extends circumferentially and radially outwardly to join tothe first fluid passages 131Xc. Furthermore, the bottom plate 131Y ofthe casing 131 is provided with a fluid passage 131 e that extendscircumferentially and radially outwardly. The fluid passage 131 e isjoined with an inlet 403 of the second pump chamber P2. These fluidpassages 131 d and 131 e extend uniformly all along the circumferentialdirection to allow liquid to flow radially outwardly in all directions,namely 360 degrees about the center axis. The fluid passage 131 d, thefirst fluid passages 131Xc, and the second fluid passage 131Xdconstitute a fluid channel passing through the first pump chamber P1.The fluid passage 131 e, the third fluid passages 131Xg, and the secondfluid passage 131Xd constitute a fluid channel passing through thesecond pump chamber P2.

Inside the container 130, there are provided a first bellows 141 and asecond bellows 142, which expand and contract with the up and downmotion of the shaft member 120. The first bellows 141 and the secondbellows 142 are arranged one above the other along the verticaldirection. The upper end of the first bellows 141 is fixedly attached tothe upper outward flange 122 a of the cylindrical portion 122 of theshaft member 120 and the lower end of the first bellows 141 is fixedlyattached to the first inward flange 131Xa of the casing 131. The upperend of the second bellows 142 is fixedly attached to the first inwardflange 131Xa of the casing 131 and the lower end of the second bellows142 is fixedly attached to the lower outward flange 122 b of thecylindrical portion 122 of the shaft member 120. The space surroundingthe outer circumference of the first bellows 141 forms the first pumpchamber P1, and the space surrounding the outer circumference of thesecond bellows 142 forms the second pump chamber P2.

Inside the container 130, there also are provided a third bellows 151and a fourth bellows 152, which expand and contract with the up and downmotion of the shaft member 120. The upper end of the third bellows 151is fixedly attached to the ceiling portion of the casing 131 and thelower end of the third bellows 151 is fixedly attached to the shaftmember 120. Thus, the opening 131 a of the casing 131 is closed. Theupper end of the fourth bellows 152 is fixedly attached to the secondinward flange 131Xb provided on the casing 131 and the lower end of thefourth bellows 152 is fixedly attached to the connecting portion 123 ofthe shaft member 120. A first space K1 is formed by the cavity in themain shaft portion 121 of the shaft member 120. A second space K2 isformed outside the third bellows 151 and inside the fourth bellows 152.A third space K3 is formed inside the first bellows 141 and the secondbellows 142 and outside the cylindrical portion 122. The first space K1,the second space K2, and the third space K3 are in communication witheach other. The space constituted by the first to third spaces K1, K2,and K3 is hermetically sealed. This space is kept in a vacuum conditionto provide heat insulation.

There are four check valves 160 including a first check valve 160A, asecond check valve 160B, a third check valve 160C, and a fourth checkvalve 160D, which are provided at different locations inside thecontainer 130. The first check valve 160A and the second check valve160B are disposed on the opposite side (lower side) of the linearactuator 110 with respect to the first pump chamber P1 and the secondpump chamber P2. The third check valve 160C and the fourth check valve160D are arranged above the first check valve 160A and the second checkvalve 160B.

The first check valve 160A and the third check valve 160C are providedin the fluid channel passing through the first pump chamber P1. Thefirst check valve 160A and the third check valve 160C block backflow ofliquid pumped by the pumping effect of the first pump chamber P1.Specifically, the first check valve 160A is provided on the upstreamside of the first pump chamber P1 and the third check valve 160C isprovided on the downstream side of the first pump chamber P1. The firstcheck valve 160A is provided in the fluid passage 131 d provided in thebottom portion of the casing 131. The third check valve 160C is providedin the fluid passage formed in the vicinity of the second inward flange131Xb provided on the casing 131. Specifically, the third check valve160C is provided in the upper portion of the first pump chamber P1. Theupper portion of the pump chamber refers to the portion of the regionthat functions as the pump chamber that is higher than its verticalcenter. In other words, the third check valve 160C is provided at aposition at which it allows gas in the first pump chamber P1 to bedischarged from it and allows the first pump chamber P1 to be filledwith liquid.

The second check valve 160B and the fourth check valve 160D are providedin the fluid channel passing through the second pump chamber P2. Thesecond check valve 160B and the fourth check valve 160D block backflowof liquid pumped by the pumping effect of the second pump chamber P2.Specifically, the second check valve 160B is provided on the upstreamside of the second pump chamber P2 and the fourth check valve 160D isprovided on the downstream side of the second pump chamber P2. Thesecond check valve 160B is provided in the fluid passage 131 e providedin the bottom plate 131Y of the casing 131. The fourth check valve 160Dis provided in the fluid passage formed in the vicinity of the firstinward flange 131Xa of the casing 131. Specifically, the fourth checkvalve 160D is provided in the upper portion of the second pump chamberP2. The upper portion of the pump chamber refers to the portion of theregion that functions as the pump chamber that is higher than itsvertical center. In other words, the fourth check valve 160D is providedat a position at which it allows gas in the second pump chamber P2 to bedischarged from it and allows the second pump chamber P2 to be filledwith liquid. The exit from the third fluid passage 131Xg is provided ata location of the same height as the location at which liquid flows outof the third check valve 160C.

<Description of the Overall Operation of the Liquid Supply System>

The overall operation of the liquid supply system will be described.When the shaft member 120 is lowered by the linear actuator 110, thefirst bellows 141 contracts and the second bellows 142 expands.Consequently, the fluid pressure in the first pump chamber P1 decreases.Then, the first check valve 160A is opened and the third check valve160C is closed. In consequence, liquid supplied from outside the liquidsupply system 10 through the inlet pipe 310 (indicated by arrow S10) istaken into the interior of the container 130 through the inlet 131 b andpasses through the first check valve 160A (indicated by arrow S11).Then, the liquid having passed through the first check valve 160A ispumped into the first pump chamber P1 through the first fluid passages131Xc in the body portion 131X of the casing 131. On the other hand, thefluid pressure in the second pump chamber P2 increases. Then, the secondcheck valve 160B is closed and the fourth check valve 160D is opened. Inconsequence, the liquid in the second pump chamber P2 is pumped into thethird fluid passages 131Xg and the second fluid passage 131Xd throughthe fourth check valve 160D (see arrow T12). Then, the liquid passesthrough the outlet 131 c and is brought to the outside of the liquidsupply system 10 through the outlet pipe 320.

When the shaft member 120 is raised by the linear actuator 110, thefirst bellows 141 expands and the second bellows 142 contracts.Consequently, the fluid pressure in the first pump chamber P1 increases.Then, the first check valve 160A is closed, and the third check valve160C is opened. In consequence, the liquid in the first pump chamber P1is pumped into the second fluid passage 131Xd provided in the bodyportion 131X through the third check valve 160C (indicated by arrowT11). Then, the liquid passes through the outlet 131 c and is brought tothe outside of the liquid supply system 10 through the outlet pipe 320.On the other hand, the fluid pressure in the second pump chamber P2decreases. Then, the second check valve 160B is opened and the fourthcheck valve 160D is closed. In consequence, liquid supplied from outsidethe liquid supply system 10 through the inlet pipe 310 (indicated byarrow S10) is taken into the interior of the container 130 through theinlet 131 b and passes through the second check valve 160B (indicated byarrow S12). Then, the liquid having passed through the second checkvalve 160B is pumped into the second pump chamber P2.

As above, the liquid supply system 10 can cause liquid to flow from theinlet pipe 310 to the outlet pipe 320 both when the shaft member 120moves downward and when the shaft member 120 moves upward. Hence, thephenomenon called pulsation can be reduced.

The fluid passage through which the cryogenic liquid flows from theinlet 131 b to the outlet 131 c via the first pump chamber P1 will behereinafter referred to as a first fluid channel. The fluid passagethrough which the cryogenic liquid flows from the inlet 131 b to theoutlet 131 c via the second pump chamber P2 will be hereinafter referredto as a second fluid channel. The first fluid channel is the passage ofthe cryogenic liquid that enters from the inlet 130 b, and then flows inthe direction indicated by arrow S11, and then flows in the directionindicated by arrow T11, and then flows to the outlet 131 c. The secondfluid channel is the passage of the cryogenic liquid that enters fromthe inlet 131 b, and then flows in the direction indicated by arrow S12,and then flows in the directions indicated by arrows T12 and T13, andthen flows to the outlet 131 c.

The height of the location at which the direction of the liquid flow inthe first fluid channel changes from the vertically upward direction tothe downward direction (see arrow T11) and the height of the location atwhich the direction of the liquid flow in the second fluid channelchanges from the vertically upward direction to the downward direction(see arrow T13) are the same.

The flow of liquid in the liquid supply system 10 during its operationis summarized as below. When the shaft member 120 moves downward, theliquid flows in the first fluid channel upstream of the first pumpchamber P1 but does not flow in the first fluid channel downstream ofthe first pump chamber P1. The liquid flows in the second fluid channeldownstream of the second pump chamber P2 but does not flow in the secondfluid channel upstream of the second pump chamber P2. When the shaftmember 120 moves upward, the liquid flows in the first fluid channeldownstream of the first pump chamber P1 but does not flow in the firstfluid channel upstream of the first pump chamber P1. The liquid flows inthe second fluid channel upstream of the second pump chamber P2 but doesnot flow in the second fluid channel downstream of the second pumpchamber P2.

<Gas Vent Pipe>

A gas vent pipe provided in the liquid supply system will be describedwith reference to FIGS. 1 to 3. FIG. 3 schematically illustrates thecross section taken along line A-A in FIGS. 1 and 2.

As illustrated in FIG. 3, radially outside the second pump chamber P2,gas vent pipes 602, the third fluid passages 131Xg connected to theoutlet 404 of the second pump chamber P2, the first fluid passages 131Xcconnected to the inlet 401 of the first pump chamber P1, and bolts 603that fasten components together are disposed at uniform circumferentialintervals.

As illustrated in FIGS. 1 and 2, the gas vent pipe 602 has a firstorifice 601 disposed in the space near the check valve 160C provided atthe outlet 402 of the first pump chamber P1 and extends in the container130 vertically downward to reach the outlet 131C. The gas vent pipe 602passes through the outlet 131 c, extends inside the outlet pipe 320, andhas a second orifice 604 located at a position higher than the firstorifice 601, as illustrated in FIG. 1. Thus, gas staying in the vicinityof the outlet in the fluid channel passing through the first pumpchamber P1 is discharged through the gas vent pipe 602 to the outside ata position higher than the first orifice 601. The gas vent pipe 602 maybe connected to a gas discharge system outside the liquid supply system10. Thus, gas is efficiently discharged out of the container 130.

<Cooling of the Liquid Supply System>

When the liquid supply system 10 is used for circulation of a cryogenicliquid such as liquid nitrogen or liquid helium, it is necessary, beforeoperation, to cool the liquid supply system 10 in an ordinarytemperature environment to a temperature as low as a low temperatureliquid used as a working liquid. The liquid used to cool the system isthe same as the low temperature liquid that is caused to flow by theliquid supply system when it is operating. The liquid used to cool thesystem may be different from the low temperature liquid that is causedto flow by the liquid supply system when it is operating.

Cooling of the system is performed by supplying low temperature liquidthrough the inlet pipe 310 to let heat exchange between the componentsof the liquid supply system 10 including the casing 131 and the lowtemperature liquid occur thereby gradually lowering the temperature ofthe components. Since the inlet 131 b and the outlet 131 c are providedon the bottom of the container 100, the low temperature liquid suppliedin the cooling process gradually fills the interior of the system, asthe level of the low temperature liquid rises. Specifically, the lowtemperature liquid fills the second pump chamber P2 firstly and then thefirst pump chamber P1. As the level of the low temperature liquid rises,components that exchange heat with the low temperature liquid increase.Thus, cooling progresses from the lower portion to the upper portion ofthe system.

<Advantages of the Liquid Supply System>

When cooling of the liquid supply system 10 is performed before using itfor the purpose of circulation of low temperature liquid, the lowtemperature liquid evaporates in the container in the early stage of thecooling process, thus the gas generated stays in the upper portion ofthe container to create a mixed state of gas and liquid. The gas firstlystays in the space near the outlet 402 of the first pump chamber P1. Thegas may stay even in the first pump chamber P1 and the second pumpchamber P2 when its amount increases. The gas may block the entrance ofthe low temperature liquid supplied through the inlet pipe 310 in orderto cool the system, making it harder for the level of the lowtemperature liquid in the container to rise. This may cause the coolingof the system not to progress efficiently because the cooling of thesystem performed by supplying the low temperature liquid progresses as aresult of heat exchange occurring between the components of the systemand the low temperature liquid that come in contact with each other.

The liquid supply system 10 can discharge the gas staying in thecontainer to the outside through the gas vent pipes 602. Thus, theliquid supply system 10 can eliminate or reduce the gas staying in theupper portion of the container in the early stage of the cooling processso that the entrance of the low temperature liquid for cooling into thecontainer tends not to be blocked. In consequence, the rise of the levelof the low temperature liquid in the container is not prevented orslowed down, and the heat exchange between the low temperature liquidand the components of the system progresses with improved efficiency.Thus, the cooling of the liquid supply system 10 by supplying the lowtemperature liquid can be carried out efficiently. This can lead to areduction in time taken to cool the liquid supply system in an ordinarytemperature environment in order to make it operable, thereby preventingan increase in the man-hour in setting-up and maintenance of the system.Moreover, the consumption of low temperature liquid in the coolingprocess can be reduced.

Others

While in the embodiment, the first orifice 601 of the gas vent pipe 602is arranged in the space near the outlet 402 of the first pump chamberP1, the location of the orifice of the gas vent pipe may be setappropriately depending on the structure of the liquid supply system.The orifice of the gas vent pipe may be located at or in the vicinity ofthe vertically highest location in the fluid channel passing through thepump chamber. This ensures discharging of the gas remaining in the upperportion of the container and prevents the liquid in the container toflow into the gas vent pipe, even when the liquid level in the containerrises. Since the gas vent pipe is disposed inside the outlet pipe 320,the gas vent pipe may be provided with heat insulation that prevents orreduces the influence of the temperature of the liquid flowing in theoutlet pipe 320 on interior space of the gas vent pipe, therebypreventing the gas flowing into the gas vent pipe from being liquefiedin it. The above-described advantages of the embodiment can be enjoyedwhen the present disclosure is applied to liquid supply systems having afluid passage leading out of the outlet of a pump chamber, extendingvertically downward on the downstream side, and then turning at afurther downstream location to extend vertically upward. The liquidsupply system has the outlet pipe 320 connected to the outlet 131 c forliquid provided on the bottom of the container, which is an example ofthe fluid passage that extends vertically downward from the outlet of apump chamber and then upward. Inside this outlet pipe, the gas vent pipeis disposed in the embodiment. However, the configuration of the fluidpassage that extends vertically downward from the outlet of a pumpchamber and then upward is not limited to this. The present disclosurecan also be applied to, for example, a liquid supply system having afluid passage that turns in a U-shape in the interior of the container.

While we have described a case where the present disclosure is appliedto a liquid supply system provided with a bellows pump including twopump chambers formed around the outer circumference of bellows that arearranged one above the other along the vertical direction (or thedirection of expansion and contraction of the bellows), liquid supplysystems to which the present disclosure can be applied are not limitedto this type. The present disclosure can be applied to pumps in generalthat take in and discharge liquid and provides the above-describedadvantageous effects when applied to liquid supply systems configured todischarge liquid from the bottom of a container in which a pump chamberis housed and bring it to a location higher than the bottom. Liquidsupply systems configured in this way discharge liquid out of thecontainer using a U-shaped pipe. In such liquid supply systems, it isnot easy to discharge gas staying in the container. If the presentdisclosure is applied, gas staying in the container can readily bedischarged to the outside.

The interior space of the vacuum container 200 outside the main systemunit 100, the intake pipe 310, and the outlet pipe 320 is kept in avacuum state to provide heat insulation. The hermetically sealed spaceconstituted by the first to third spaces K1, K2, and K3 is kept in avacuum state to provide heat insulation. Alternatively, these spaces mayalso be supplied with cryogenic liquid to keep the temperature of liquidflowing in a circulation fluid passage low.

REFERENCE SIGNS LIST

-   10: liquid supply system-   100: main system unit-   110: linear actuator-   120: shaft member-   121: main shaft portion-   122: cylindrical portion-   122 a: upper outward flange-   122 b: lower outward flange-   123: connecting portion-   130: container-   131: casing-   131 a: opening-   131 b: inlet-   131 c: outlet-   131 d: fluid passage-   131 e: fluid passage-   131X: body portion-   131Xa: first inward flange-   131Xb: second inward flange-   131Xc: first fluid passage-   131Xd: second fluid passage-   131Xg: third fluid passage-   131Y: bottom plate-   141: first bellows-   142: second bellows-   151: third bellows-   152: fourth bellows-   160: check valve-   160A: first check valve-   1606: second check valve-   160C: third check valve-   160D: fourth check valve-   200: vacuum container-   310: inlet pipe-   320: outlet pipe-   401: inlet of first pump chamber-   402: outlet of first pump chamber-   403: inlet of second pump chamber-   404: outlet of second pump chamber-   601: first orifice-   602: gas vent pipe-   603: bolt-   604: second orifice-   P1: first pump chamber-   P2: second pump chamber

1. A liquid supply system comprising: a container having an inlet and anoutlet for liquid and provided with a pump chamber inside it; an outletpipe through which liquid discharged from the outlet is brought tooutside; a fluid channel through which liquid flows, the fluid channelleading out of the inlet, passing through the pump chamber, andextending vertically downward from the pump chamber to the outlet; and agas vent pipe having a first orifice disposed in the fluid channel and asecond orifice disposed in the fluid channel downstream of the firstorifice, wherein the second orifice is located at vertically higherlevel than the first orifice.
 2. The liquid supply system according toclaim 1, wherein the second orifice is disposed in the outlet pipe. 3.The liquid supply system according to claim 1, comprising: a shaftmember that moves vertically upward and downward in the container; and afirst bellows and a second bellows disposed one above the other alongthe vertical direction, each of which expands and contracts with upwardand downward motion of the shaft member; wherein the pump chamberincludes a first pump chamber formed by a space surrounding the outercircumference of the first bellows and a second pump chamber formed by aspace surrounding the outer circumference of the second bellows, thefluid channel includes a first fluid channel through which liquid flowsfrom the inlet to the outlet via the first pump chamber and a secondfluid channel through which liquid flows from the inlet to the outletvia the second pump chamber, and the gas vent pipe is provided in atleast one of the first and second fluid channels.
 4. The liquid supplysystem according to claim 3, wherein the first pump chamber is disposedabove the second pump chamber and the first orifice is located above theoutlet of the first pump chamber.